Low budget, small form factor build

My brother is wanting a cheap computer for medium photo/video editing, writing/blogging, and light gaming. Future potential as an htpc would be nice, not required as that's just an afterthought.

Budget: ~$400$550, Can use a build that costs a little more if the parts regularly go on sale, will buy when they do

Parts: USB3, small form factor is a must (basically anything smaller than standard atx). No LEDs, and reasonably quiet. Obviously it still needs to stay cool, but can probably stick with stock cooler since he won't be overclocking.

He wants to be able to use it for a while, as he only upgrades every 4-5 years. I've built before, never done a smaller form factor though. Thanks in advance for any suggestions.

my brother got all excited the day after I talked to him about the build that he bought an OCZ ModXStream Pro OCZ500MXSP 500W because he saw it on a deal site that basically had a free DVD burner.

He really wanted USB3 on the board and is willing to up the budget for it, but is he better off buying a mobo without it and getting a PCIe card to add it later (or right away)? I did a quick search and found these two boards GA-785GMT-USB3 and GA-880GMA-UD2H. MSI has at least one, 890GXM-G65, but they seem to have issues with quality and poor rebate returns. Also I've been unclear if the GB boards can unlock cores of non-BE cpu's, since the 440 could get a 4th?